Make the message length in the sync pipe message header 3 bytes of

binary data, so the maximum message length can be up to 2^24-1.

Add a #define for that message size, and have it be 4096, for now, as
that was the size of the buffer used to read sync pipe messages.

Clean up white space.

When displaying an error message from the capture child, don't use it as
a format string - it could conceivably contain "%"s.  Instead, format it
with "%s".

svn path=/trunk/; revision=16541

1 files changed, 29 insertions, 18 deletions

diff --git a/capture_sync.c b/capture_sync.c
index 124e6ad446..86d9b96f7e 100644
--- a/capture_sync.c
+++ b/capture_sync.c
@@ -103,6 +103,15 @@ static const char *sync_pipe_signame(int);
 static gboolean sync_pipe_input_cb(gint source, gpointer user_data);
 static void sync_pipe_wait_for_child(capture_options *capture_opts);
 
+/*
+ * Maximum length of sync pipe message data.  Must be < 2^24, as the
+ * message length is 3 bytes.
+ * XXX - this must be large enough to handle a Really Big Filter
+ * Expression, as the error message for an incorrect filter expression
+ * is a bit larger than the filter expression.
+ */
+#define SP_MAX_MSG_LEN	4096
+
 /* Size of buffer to hold decimal representation of
    signed/unsigned 64-bit int */
 #define SP_DECISIZE 20
@@ -110,10 +119,10 @@ static void sync_pipe_wait_for_child(capture_options *capture_opts);
 /*
  * Indications sent out on the sync pipe.
  */
-#define SP_FILE	        'F'	    /* the name of the recently opened file */
+#define SP_FILE         'F'     /* the name of the recently opened file */
 #define SP_ERROR_MSG    'E'     /* error message */
 #define SP_PACKET_COUNT 'P'     /* count of packets captured since last message */
-#define SP_DROPS        'D'	    /* count of packets dropped in capture */
+#define SP_DROPS        'D'     /* count of packets dropped in capture */
 #define SP_QUIT         'Q'     /* capture quit message (from parent to child) */
 
 
@@ -123,18 +132,21 @@ static void sync_pipe_wait_for_child(capture_options *capture_opts);
 static void
 pipe_write_block(int pipe, char indicator, int len, const char *msg)
 {
-    char lenbuf[3+1+1]; /* 3 digit len + indicator + zero terminator */
+    guchar header[3+1]; /* indicator + 3-byte len */
     int ret;
 
     /*g_warning("write %d enter", pipe);*/
 
-    g_assert(len < 1000);
     g_assert(indicator < '0' || indicator > '9');
+    g_assert(len <= SP_MAX_MSG_LEN);
 
-    /* write header (3 digit len + indicator) */
-    g_snprintf(lenbuf, 5, "%03u%c", len, indicator);
+    /* write header (indicator + 3-byte len) */
+    header[0] = indicator;
+    header[1] = (len >> 16) & 0xFF;
+    header[2] = (len >> 8) & 0xFF;
+    header[3] = (len >> 0) & 0xFF;
 
-    ret = write(pipe, lenbuf, strlen(lenbuf));
+    ret = write(pipe, header, sizeof header);
     if(ret == -1) {
         return;
     }
@@ -155,17 +167,17 @@ pipe_write_block(int pipe, char indicator, int len, const char *msg)
 
 
 /* read a message from the sending pipe in the standard format 
-   (3 digit message length (excluding length and indicator field), 
-   1 byte message indicator and the rest is the message) */
+   (1-byte message indicator, 3-byte message length (excluding length
+   and indicator field), and the rest is the message) */
 static int
 pipe_read_block(int pipe, char *indicator, int len, char *msg) {
     int required;
     int newly;
-    char header[4];
+    guchar header[4];
     int offset;
 
 
-    /* read header (3 digit len and indicator) */
+    /* read header (indicator and 3-byte length) */
     required = 4;
     offset = 0;
     while(required) {
@@ -186,8 +198,8 @@ pipe_read_block(int pipe, char *indicator, int len, char *msg) {
     }
 
     /* convert header values */
-    *indicator = header[3];
-    required = atoi(header);
+    *indicator = header[0];
+    required = header[1]<<16 | header[2]<<8 | header[3];
 
     /* only indicator with no value? */
     if(required == 0) {
@@ -247,7 +259,7 @@ sync_pipe_errmsg_to_parent(const char *errmsg)
 void
 sync_pipe_drops_to_parent(int drops)
 {
-	char tmp[SP_DECISIZE+1+1];
+    char tmp[SP_DECISIZE+1+1];
 
 
     g_snprintf(tmp, sizeof(tmp), "%d", drops);
@@ -577,13 +589,12 @@ static gboolean
 sync_pipe_input_cb(gint source, gpointer user_data)
 {
   capture_options *capture_opts = (capture_options *)user_data;
-#define BUFSIZE	4096
-  char buffer[BUFSIZE+1];
+  char buffer[SP_MAX_MSG_LEN+1];
   int  nread;
   char indicator;
 
 
-  nread = pipe_read_block(source, &indicator, BUFSIZE, buffer);
+  nread = pipe_read_block(source, &indicator, SP_MAX_MSG_LEN, buffer);
   if(nread <= 0) {
     g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "sync_pipe_input_cb: child has closed sync_pipe");
 
@@ -624,7 +635,7 @@ sync_pipe_input_cb(gint source, gpointer user_data)
     break;
   case SP_ERROR_MSG:
     g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_MESSAGE, "Error message from child: \"%s\"", buffer);
-    simple_dialog(ESD_TYPE_ERROR, ESD_BTN_OK, buffer);
+    simple_dialog(ESD_TYPE_ERROR, ESD_BTN_OK, "%s", buffer);
     /* the capture child will close the sync_pipe, nothing to do for now */
     break;
   case SP_DROPS: